a) Field of the Invention
The present invention relates to a method of arranging or configuring non-magnetic substances such as non-magnetic particles. The invention is applicable to technical fields of micro grinding work, micro component assembly, and micro decorating work.
b) Description of the Related Art
A grindstone to be used for a micro grinding work is made of diamond abrasive grains having a diameter of several .mu.m or smaller fixed together with binder such as resin. Conventionally, a distribution of diamond abrasive grains on the surface of a grindstone has not be controlled but is left at random. It has been found recently that if diamond abrasive grains are arranged regularly, the precision and efficiency of a grinding work can be improved considerably. However, a work of holding and handling a large number of diamond abrasive grains one grain after another is not practical from the viewpoint of work cost. A method has been proposed by which magnetic material is coated on each diamond abrasive grain and coated grains are forcibly arranged by a magnetic force of a magnetic field externally applied. It is, however, very high in cost to coat a magnetic material on a diamond abrasive grain, and moreover since the amount of magnetic material coated on the grain is small, a arrangement or configuration of abrasive grains is not achieved unless a. high magnetic field of about 1 T is applied. In assembling micro mechanical components of a micro machine presently under development, it is necessary to align the directions of these micro components and arrange them regularly. Most of these micro components are often made of non-magnetic substance. Also in the field of micro decorating work, it is necessary to control the distribution of non-magnetic particles such as diamond particles. Adequate techniques of easily handling such non-magnetic particles such as diamond particles have not been developed as yet.
The present inventor has developed a non-magnetic substance arrangement method (refer to the specification and drawings of JP-A-9-222150 entitled "Non-Magnetic Substance Arrangement Method"). The contents of the developed non-magnetic substance arrangement method disclose that non-magnetic particles are mixed with a magnetic fluid and the surface of a substrate is coated with the magnetic fluid. A uniform d.c. magnetic field is applied vertically or horizontally to the substrate, or an a.c. magnetic field superposed upon the d.c. magnetic field is applied, to thereby arrange or configure the non-magnetic particles in an in-plane of the substrate or cubically. The developed non-magnetic substance arrangement method can regularly arrange non-magnetic particles such as abrasive particles very easily and very cost effectively and can be applied to techniques such as micro grinding work, micro component assembly, and micro decorating work. With the developed non-magnetic substance arrangement method, however; the arrangement interval .lambda. of particle chains depends upon various factors such as a size and specific gravity of a particle, a particle concentration in the magnetic fluid, an interface state between particles, and an externally applied magnetic field intensity. Therefore, it is difficult and unstable to control the arrangement of non-magnetic particles only by the intensity of an externally applied uniform magnetic field. In particular, if the amount of non-magnetic particles contained in the magnetic fluid increases, adjacent non-magnetic particle chains may couple each other. In this case, a practically usable control is difficult.